This invention relates to acoustic horns, and more particularly, to an apparatus and method for verification of acoustic horn performance.
An acoustic horn is a gas operated device that produces low frequency, e.g., 60 Hertz to 300 Hertz, high-energy sound waves and is used for cleaning in many industrial applications. The sound waves that are emitted from an acoustic horn resonate and dislodge dust or ash deposits from surfaces. A significant advantage of an acoustic horn is that the acoustic horn can be used to remove dust or debris from locations that are difficult to clean by conventional methods. This includes surfaces that are inaccessible or surfaces that are subject to a high temperature or a high voltage. Therefore, there are numerous applications for acoustic horns. For example, in industrial or utility boilers, acoustic horns are used to clean boiler tubes and heat exchangers. In addition, acoustic horns are often used to clean Selective Catalytic Reduction (SCR) equipment. In these two applications, the acoustic horns are used to supplement or replace conventional steam soot blowers. For industrial, gas pollution, control filters, including electrostatic precipitators and bag houses, acoustic horns are utilized to clean the internal components. In these applications, the acoustic horns are utilized to supplement or replace existing conventional mechanical methods. Acoustic horns are also utilized to clean surfaces associated with material handling operations including collecting hoppers, fans, silos and ductwork.
The intensity at which an acoustic horn operates and its frequency are related to the cleaning effect. There are a number of factors in real world applications that may affect this intensity. These factors include the supply gas pressure and the gas flow. For example, when the supply gas pressure is reduced or the gas piping is restricted, the intensity of the acoustic horn will be reduced. Moreover, when the driver components for the acoustic horn are worn or the acoustic horn malfunctions, then the intensity of the acoustic horn will also be reduced.
There are two common methods for testing the intensity of an acoustic horn. The first method is to measure the supply gas pressure while the acoustic horn is being operated and the second method is to disassemble the driver components associated with the acoustic horn and measure these driver components for wear. Both processes provide a very indirect measurement of intensity. The second process, which involves the disassembly and measurement of the driver components, is very slow and tedious. Also, this second process results in significant downtime for the acoustic horn.
One method for measuring the intensity and frequency of an acoustic horn in real time is by using a microphone. The microphone is placed near the area being cleaned. However, this cleaning is typically accomplished with more than one acoustic horn. When an acoustic horn sounds, the microphone can detect the amplitude and the frequency of the sound. However, a significant problem arises when more than one acoustic horn sounds simultaneously since the microphone cannot differentiate between the two acoustic horns. Also, the measured intensity is a function of the position of the microphone and the surrounding acoustics at that particular location. Moreover, an additional problem is the background noise or vibration that may be present where either the acoustic horn or the microphone is mounted. Furthermore, a microphone cannot measure absolute pressure or a pressure pulse followed by a vacuum pulse or a negative pressure pulse. All of these variables can lead to uncertainty in the measurement process. Since the microphones are located in areas being cleaned from dust and debris, these microphones may potentially be in an atmosphere that is corrosive, dust-laden and/or subject to a high temperature or voltage.
Another problem that arises when utilizing acoustic horns is that since the acoustic horn operates in a dust-laden environment, some of this debris will enter the bell and driver of the acoustic horn. This can be very detrimental to the operation of the acoustic horn. Therefore, purge gas is sometimes supplied to the acoustic horn to pressurize the bell and prevent the accumulation of this material within the acoustic horn. Consequently, it is necessary to know the ambient positive or the negative pressure of the acoustic horn.
The present invention is directed to overcoming one or more of the problems set forth above.
In one aspect of this invention, a system for verification of acoustic horn performance is disclosed. This system includes a pressure detecting mechanism that converts at least one vibratory sound energy pulse, which is followed by at least one vacuum pulse or at least one negative pressure pulse, into a signal that is proportional to a level of sound energy, wherein the pressure detecting mechanism is operable to be connected to an acoustic horn.
In another aspect of this invention, a method for verification of acoustic horn performance is disclosed. This method includes operatively connecting an acoustic horn to a pressure detecting mechanism that converts at least one vibratory sound pulse, which is followed by at least one vacuum pulse or at least one negative pressure pulse, to a signal that is proportional to a level of sound energy.